Flashlights and portable lanterns are used extensively in this country and abroad Almost every home and business has at least one flashlight or portable lantern, and many homes and businesses have several flashlights, including at least one emergency flashlight. In addition, many people carry at least one flashlight in their automobiles, recreational vehicles, trucks, boats, or airplanes. The majority of the flashlights and portable lanterns are used on an infrequent basis, that is, during an emergency situation where there has been a power failure or when it is not convenient to use a light source powered by a conventional household current, such as outdoor uses.
The majority of flashlights and batteries are powered by dry-cell non-rechargeable batteries. Non-rechargeable alkaline batteries sold under the trademarks Eveready, Duracell, Ray-O-Vac, and the like, have a number of advantages over rechargeable batteries. Principally, on a weight-to-weight and volume-to-volume basis, the alkaline can supply three to four times the wattage of a rechargeable battery. In addition, non-rechargeable dry-cell batteries put out a higher voltage (about 1.5 volts) than rechargeable dry-cell-type batteries (about 1.2 volts). Rechargeable batteries, even if not in use, have to be periodically recharged to keep the batteries from falling below a defined charge level to prevent permanent damage to the batteries. Alkaline batteries which are used infrequently can have a shelf-or storage-life of from three to five years. During this period, no maintenance of the batteries is required. In contrast, most rechargeable batteries will completely discharge within six months of their last recharge. Most rechargeable batteries are permanently damaged if they are allowed to completely discharge. Accordingly, most flashlights and portable lanterns are powered with non-rechargeable dry cells, including alkaline cells, because of their relatively long shelf-life, output voltage, and relatively high charge or power capacity.
Most individuals test their flashlight batteries by turning the flashlight on. If the flashlight bulb lights up, the individual is satisfied that the batteries are functional. A much smaller group of people will disassemble the flashlight and test the batteries on a battery tester to determine the condition of the batteries. An even smaller group will test the batteries under both loaded and unloaded conditions to measure the voltage drop, which is a sensitive indicator of the remaining capacity of the batteries. Although it is not complicated to test batteries, it is time-consuming to disassemble the flashlight, remove the batteries, test the batteries, and, if they pass the test, reinstall the batteries and reassemble the flashlight.
Accordingly, it is an object of the present invention to provide a flashlight or a portable lantern having a built-in battery tester which permits the batteries to be quickly tested within the flashlight. Thus, with the flashlight of the present invention, the user can quickly and effortlessly determine the strength of the batteries. The user is thereby more likely to routinely check the condition of the batteries, and thus maintain the readiness of the flashlight or portable lantern.